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Exfoliative
Dermatoses
(Skin Disorders Characterized
by the Presence of Scales)
Basics
OVERVIEW
• Excessive or abnormal shedding of skin cells, resulting in the
clinical presentation of accumulations of surface skin cells, such
as seen in dandruff (known as “scales”)
• “Exfoliative” refers to the detachment and shedding of surface
skin cells; “dermatosis” (plural, “dermatoses”) is the medical
term for any skin abnormality or disorder
• “Primary” refers to a condition that occurs first in the skin;
“secondary” refers to changes that occur following the primary
disease—for example, the skin may be inflamed due to a
nutritional deficiency (primary condition) and become infected
by bacteria invading the inflamed skin (secondary condition) or
the skin changes are secondary to the presence of some other
problem or abnormality (such as the presence of parasites on
the skin)
SIGNALMENT/DESCRIPTION OF PET
Species
• Dogs
• Cats
Breed Predilections
• Primary exfoliative dermatoses—cocker spaniels, English springer spaniels, West Highland white terriers, basset
hounds, Doberman pinschers, Irish setters, Labrador retrievers, Siberian huskies, Alaskan malamutes,
dachshunds, chow chows, Yorkshire terriers, poodles, Great Danes, whippets, salukis, Italian greyhounds,
standard poodles, Samoyeds, Akitas, vizslas, golden retrievers
• Primary seborrhea (excessively oily or dry scaling of the skin)—Persian kittens
• Secondary exfoliative dermatoses—any breed of dog or cat
Mean Age and Range
• Primary exfoliative dermatoses—apparent by 2 years of age
• Primary seborrhea (excessively oily or dry scaling of the skin)—newborn Persian kittens
• Secondary exfoliative dermatoses—any age
SIGNS/OBSERVED CHANGES IN THE PET
• Excessive scaling
• Smelly or malodorous skin; “rancid fat” odor is common
• Itchiness (known as “pruritus”)
• Oily skin and hair
• Dry or greasy accumulations of surface skin cells, as seen in dandruff (scales); accumulations may be fine or
coarse; may be located throughout the hair coat or in localized areas
• Hair follicles may become filled with oil and skin cells (known as “comedones”)
• Accumulation of debris that adheres to hair shaft (known as “follicular casts”)
• “Candle wax”–like deposits on hair
• Hair loss (known as “alopecia”)
• Secondary skin inflammation, caused by the yeast Malassezia (known as “secondary Malassezia dermatitis”)
CAUSES AND RISK FACTORS
Primary Exfoliative Dermatoses
• Primary excessively dry or oily scaling of the skin (known as “seborrhea”) of unknown causes (so-called
“idiopathic seborrhea”) that is a primary disorder in the normal replacement and shedding of skin cells (known
as a “keratinization disorder”)—breeds at highest risk: cocker spaniels, English springer spaniels, West Highland
white terriers, basset hounds, Doberman pinschers, Irish setters, and Labrador retrievers; dry (known as
“seborrhea sicca”) and greasy or oily (known as “seborrhea oleosa”) forms exist, but determination of type has
little prognostic value
• Skin disorder that responds to treatment with vitamin A (known as “vitamin A–responsive dermatosis”)—
nutritionally responsive; seen primarily in young cocker spaniels; clinical signs similar to severe idiopathic
seborrhea; distinguished by response to dietary vitamin A supplementation
• Skin disorder that responds to treatment with zinc (known as “zinc-responsive dermatosis”)—nutritionally
responsive; results in hair loss (alopecia); accumulations of surface skin cells, as seen in dandruff (scales); dried
discharge on the surface of the skin lesion (known as a “crust”); and reddening of the skin (known as
“erythema”) around the eyes, ears, feet, lips, and other external orifices; two syndromes are seen: (1) young adult
dogs, especially Siberian huskies and Alaskan malamutes, and (2) rapidly growing, large-breed puppies
• Abnormalities in the development of the skin and related structures (such as hair follicles)—abnormal
development of the hair follicles or hair (known as “follicular dysplasia”); seen as hair loss (alopecia) in color
mutant or dilution pets; represent abnormalities in deposition of melanin pigments (responsible for the color of
the skin and hair) of the hair shaft and structural hair growth; breeds commonly affected: blue and fawn
Doberman pinschers, Irish setters, dachshunds, chow chows, Yorkshire terriers, poodles, Great Danes,
whippets, salukis, and Italian greyhounds; signs include failure to regrow blue or fawn hair with normal “point”
hair growth, excessive accumulations of surface skin cells, as seen in dandruff (scales), hair follicles filled with
oil and skin cells (comedones), and skin infection characterized by the presence of pus (secondary pyoderma)
• Thickening of the skin (known as “hyperkeratosis”) of the nose and pads of the feet of unknown cause (so-called
“idiopathic nasodigital hyperkeratosis”)—excessive accumulation of surface skin cells (scales) and dried
discharge on the surface of the skin lesion (crusts) on the tough, hairless skin of the nose (known as the “nasal
planum”) and footpad margins; possibly an aging change, seen in spaniels and Labrador retrievers; may result
in cracking and secondary bacterial infection that can be quite painful
• Inflammation of the sebaceous glands, the glands that produce oils in the hair coat (condition known as
“sebaceous adenitis”)—inflammatory disease; may be of unknown cause (so-called “idiopathic sebaceous
adenitis”); three specific syndromes seen: (1) middle-aged standard poodles and Samoyeds—characteristic
patchy or widespread (diffuse) hair loss (alopecia) and excessive accumulation of surface skin cells, as seen in
dandruff (scales); accumulation of debris that adheres to hair shaft (follicular casts); most dogs are healthy; (2)
Akitas—frequently develop severe and deep bacterial skin infection characterized by the presence of pus
(pyoderma); (3) vizslas—disease appears distinctly different and is characterized by the presence of nodular,
inflammatory lesions (known as “granulomas”); other breeds can be affected but are less likely than the breeds
indicated previously
• Abnormal development of the top surface of the skin (known as the “epidermis”; condition known as “epidermal
dysplasia”) and congenital (present at birth) disorders of the normal replacement and shedding of skin cells
(keratinization disorder; condition known as “ichthyosis”)—rare and severe congenital disorder of
keratinization; reported in West Highland white terriers and golden retrievers; generalized accumulations of
surface skin cells, as seen in dandruff (scales) and dried discharge on the surfaces of the skin lesions (crusts) at
an early age; secondary bacterial and yeast infections are common
• Primary excessively oily scaling of the skin (primary seborrhea)—newborn Persian kittens
Secondary Exfoliative Dermatoses
• Increased sensitivity or reaction in the skin to the presence of a foreign agent (known as “cutaneous
hypersensitivity”)—atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the
environment [such as pollen] that normally would not cause any health problems); flea-bite allergy; food
allergy; and inflammation of the skin secondary to contact with some substance to which the pet reacts or to
which the skin becomes irritated (known as “contact dermatitis”); characterized by itchiness (pruritus) and
secondary skin trauma and irritation
• Parasites of the skin—sarcoptic mange or scabies; demodectic mange (demodicosis) and “walking dandruff”
(cheyletiellosis)
• Skin infection characterized by the presence of pus (pyoderma)
• Bacterial infection of the hair follicles (known as “bacterial folliculitis”)
• Skin inflammation due to Malassezia, a yeast
• A fungal infection affecting the skin, hair, and/or nails (known as “dermatophytosis”)
• Hormonal disorders (known as “endocrinopathies”)—inadequate production of thyroid hormone (known as
“hypothyroidism”) and excessive production of steroids by the adrenal glands (known as
“hyperadrenocorticism” or “Cushing's syndrome”) commonly produce excessive accumulation of surface skin
cells, as seen in dandruff (scales); secondary skin infection characterized by the presence of pus (secondary
pyoderma) common in both syndromes; other hormonal abnormalities (such as sex-hormone abnormalities,
excessive production of thyroid hormone [known as “hyperthyroidism”], and diabetes mellitus [“sugar
diabetes”]) also may be associated with excessive scaling
• Age—senior pets may have a dull, brittle, and scaly hair coat; changes may be caused by natural alterations
associated with aging; no specific defect identified
• Nutritional disorders—skin disorders may occur with malnutrition and feeding generic dog food; result in
accumulation of surface skin cells, as seen in dandruff (scales) from abnormalities in the normal replacement
and shedding of skin cells (keratinization)
• Diseases in which the body's immune system attacks its own skin (known as “autoimmune skin diseases”)—
pemphigus complex; cutaneous and systemic lupus erythematosus; often see areas of hair loss (alopecia) and
scaling
• Tumors, cancer, and precancerous disorders of the skin—may produce hair loss (alopecia) and accumulation of
surface skin cells, as seen in dandruff (scales) when skin is damaged
• Miscellaneous—any disease process may result in excessive accumulation of surface skin cells, as seen in
dandruff (scales)
• Exfoliative disorders (“exfoliative” refers to the detachment and shedding of surface skin cells)—rare in cats;
include tail-gland hyperplasia or “stud tail,” in which the sebaceous glands at the base of the tail enlarge and
overproduce oil secretions, leading to matted hair and scales in the hair coat; exfoliative skin inflammation
(known as “exfoliative dermatitis”) associated with thymoma, a type of tumor of the thymus (the thymus is an
organ located in the front of the chest, near the neck; it is part of the immune system)
Treatment
HEALTH CARE
• Diagnose and control all treatable primary and secondary diseases
• Frequent and appropriate treatment applied to the skin directly (known as “topical therapy”)—cornerstone of
proper treatment
• Frequent baths, as directed by your pet's veterinarian
• Recurrence of secondary infections may require repeated treatment and further diagnostic testing
• Maintaining control of these skin disorders is often a lifelong commitment
DIET
• Depends on underlying cause
• Dietary modification may be necessary for cases of suspected food allergy and for nutritionally related skin
disorders
SURGERY
• Skin biopsy may be necessary to determine diagnosis
• Surgical removal of skin tumors/cancer
Medications
Medications presented in this section are intended to provide general information about possible treatment. The
treatment for a particular condition may evolve as medical advances are made; therefore, the medications should
not be considered as all inclusive
TREATMENT APPLIED TO THE SKIN DIRECTLY (TOPICAL THERAPY)
Shampoos
• Contact time of shampoo (that is, shampoo must be left on body for a certain amount of time)—5–15 minutes
generally required, as directed by your pet's veterinarian
• Hypoallergenic shampoo—useful only in mild cases of dry scale and to maintain skin condition after the primary
disease has been controlled
• Sulfur/salicylic acid–containing shampoos—soften and loosen crusts and scales on the skin (known as
“keratolytic shampoos”) and slow the growth of bacteria (known as a “bacteriostatic property”); excellent first
choice for the moderately scaly pet; not overly drying
• Benzoyl peroxide shampoo—strong action to soften and loosen crusts and scales on the skin (keratolytic
shampoo), destroys bacteria or slows their growth and multiplication (known as an “antimicrobial property”),
and flushes out the hair follicles; may cause irritation and severe dryness; frequently used for recurrent bacterial
infection and/or extreme greasiness
• Ethyl lactate shampoo—less effective than benzoyl peroxide for flushing out the hair follicles and not as effective
against bacteria, but not as irritating or drying; most useful for moderate bacterial infection of the hair follicles
(bacterial folliculitis) and dry scale
• Chlorhexidine—a chemical antiseptic (compounds that kill or slow the growth of bacteria and other
microorganisms); mildly drying; useful for moderate bacterial infections of the hair follicles (bacterial
folliculitis) and skin inflammation caused by the yeast Malassezia (Malassezia dermatitis)
• Tar shampoos—soften and loosen crusts and scales on the skin (keratolytic shampoos) and decrease itchiness
(known as an “antipruritic property”); less degreasing than benzoyl peroxide; use for moderate scale associated
with itchiness (pruritus); can be irritating; might be a substance linked to cancer (known as a “carcinogen”); not
widely available in veterinary products
Moisturizers
• Excellent for restoring skin hydration (frequent shampooing may result in excessive dryness and itchiness
[pruritus]) and increasing effectiveness of subsequent shampoos
• Humectants (moisturizers that attract water into the surface of the skin)—enhance hydration of the skin; at high
concentrations may soften and loosen crusts and scales on the skin
• Propylene glycol spray (50–75% dilution with water) applied frequently as directed by your pet's veterinarian
• Microencapsulation (moisturizers are placed in tiny capsules that allow prolonged effect)—may improve the
residual activity of moisturizers by permitting sustained release after bathing
• Emollients (agents that soften and soothe the skin)—coat the skin; smooth the roughened surfaces produced by
excessive scaling
GENERALIZED (SYSTEMIC) THERAPY
• Specific causes of exfoliative dermatoses require specific treatments (such as thyroid hormone [thyroxine]
replacement for pets with inadequate levels of thyroid hormone [hypothyroidism]; zinc supplements for zincresponsive dermatosis)
• Antibiotics administered by mouth or injection—always indicated for secondary skin infection characterized by
the presence of pus (secondary pyoderma)
• Retinoid drugs—varied success for seborrhea of unknown cause (idiopathic seborrhea) or primary seborrhea;
reports of individual response to retinoids in pets that do not respond to other treatments (known as
“refractory” cases); very strict regulations have made it difficult to prescribe and dispense synthetic retinoids
• Cyclosporine (medication to decrease the immune response) may be used in some cases
• Ketoconazole (an antifungal drug)—may be used for treatment of severe skin inflammation due to Malassezia, a
yeast
Follow-Up Care
PATIENT MONITORING
• Antibiotics and treatment applied to the skin directly (topical therapy)—monitor response every 3 weeks; pets
may respond differently to the various topical therapies
• Seasonal changes, development of additional diseases (especially increased sensitivity or reaction in the skin to
the presence of a foreign agent [cutaneous hypersensitivity]), and recurrence of skin infection characterized by
the presence of pus (pyoderma)—may cause previously controlled pets to worsen; reevaluation critical for
determining if new factors are involved and if changes in therapy are necessary
• Hormonal disorders (endocrinopathies)—bloodwork to monitor thyroid levels following treatment for
inadequate levels of thyroid hormone (hypothyroidism), should be performed 4–6 hours following
administration of thyroid medication—frequency of thyroid monitoring as recommended by your pet's
veterinarian; adrenocorticotropic hormone (ACTH)-stimulation tests should be performed for proper
management of pets with excessive production of steroids by the adrenal glands (hyperadrenocorticism or
Cushing's disease)
• Some autoimmune disorders—reevaluate frequently during the initial phase of treatment; less often after
remission
• Medications to decrease the immune response (known as “immunosuppressive therapy”)—frequent bloodwork
(such as complete blood counts [CBCs] and serum chemistries) and urinalyses with bacterial culture to monitor
for complications
• Retinoid drugs—bloodwork (serum chemistries, including triglycerides); Schirmer tear tests to monitor the eyes
for changes in tear production
• Ketoconazole—bloodwork (serum chemistries)
PREVENTIONS AND AVOIDANCE
• Depend on underlying cause
POSSIBLE COMPLICATIONS
• Depend on underlying cause
EXPECTED COURSE AND PROGNOSIS
• Depend on underlying cause
Key Points
• Some causes of excessive or abnormal shedding of skin cells, resulting in the clinical presentation of
accumulations of surface skin cells (such as dermatophytosis and several parasitic skin diseases), have either
zoonotic potential or the ability to produce lesions in people; “potential zoonoses” are diseases that can be
passed from animals to people
• Diagnose and control all treatable primary and secondary diseases
• Frequent and appropriate treatment applied to the skin directly (known as “topical therapy”)—cornerstone of
proper treatment
• Frequent baths, as directed by your pet's veterinarian
• Recurrence of secondary infections may require repeated treatment and further diagnostic testing
• Maintaining control of these skin disorders is often a lifelong commitment
Enter notes here
Blackwell's Five-Minute Veterinary Consult: Canine and Feline, Fifth Edition, Larry P. Tilley and Francis W.K. Smith, Jr. © 2011 John Wiley & Sons,
Inc.